JPH0465022A - Wire conductor for automobile - Google Patents

Abstract

PURPOSE:To attain lightness by specifying the tensil strength of element conductor to be stranded, the total sectional area, breakage load, breakage elongation of the conductor stranded, and composing the element conductor of cupper and the like in its surface layer and steel-made complex element conductor in its core part. CONSTITUTION:An element conductor is prepared by refining heat treatment or annealing treatment to have a tensile strength (t) of 80-160kgf and breakage elongation E of 2% or more, and stranded to have the conductor sectional area (D) of 0.05-0.3mm, conductor breakage load T of 6kgf or more and breakage elongation E of 2% or more. The element conductor with specific conductance of 25% or more (IACS) is composed of surface layer made of cupper or cupper alloy and core part made of steel containing one kind or more of 0.05-0.2% of Si, 0.3-1.9% of Mn, 0.5-0.5% of Ni, 0.2-2.0% of Cr, 0.1-1.0% of Mo, 0.01-0.2% of Nb, 0.01-1.0% of V, 0.001-0.006% of B, 0.1-1.0% of Be, 0.02-1.0% of Al, 0.02-1.0% of Ti, 0.05% or less of both P and S as inevitable impurities, and 0.3% or less of Cu. It is thus possible to reduce the weight of wire conductor for an automobile.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a T4 wire conductor for automobiles that is lightweight.

[Conventional technology]

JISC31 is mainly used as a wire conductor for wiring in automobiles.
Annealed copper wire as specified in 02 or wires plated with tin are used, and this is coated with an insulator such as vinyl chloride, cross-linked vinyl, or cross-linked polyethylene, and used as an electric wire. there was.

However, as the performance of automobiles increases, the number of various control circuits increases, resulting in an increase in the number of wiring locations within the automobile.Therefore, there is an increasing demand for weight reduction while maintaining reliability. Conventional wire conductors tend to be avoided.

Electric wires for control circuits, which account for most of the wiring, carry signal currents, so most of them have an allowable current of less than IA, but conventional wire conductors have a diameter that is thicker than the electrically required diameter to ensure mechanical strength. This is because it increases the weight of the vehicle.

Therefore, in an attempt to reduce the weight of this type of electric wire, some studies have considered using aluminum (including alloys, the same hereinafter) for the conductor. In addition, 0.3-0.9% Sn copper alloy wire and 4-8
Conductors using materials such as phosphor bronze containing %Sn have also been developed and are used in some areas (Special Publications No. 60-30043, No. 6l-
29133).

In addition, the tensile strength of the conductor is 90 to 140 kgf/am”,
Electric wires with a conductor breaking load of 6 kgf or more have also been developed.

[Problem to be solved by the invention]

Aluminum is weak in strength, and in order to obtain sufficient wire strength, it is essential to take measures such as increasing the outer diameter or increasing the number of twisted wires in the conductor, which increases the amount of insulator used and the wiring space. In addition to increasing costs, sufficient weight reduction effects cannot be expected.

In addition, many terminals are used in automobile wiring, but these terminals have various problems such as electrical corrosion and poor solderability.

On the other hand, in the wire conductor shown in the above-mentioned publication, the strength of the copper wire is increased by adding Sn, which makes it possible to reduce the cross-sectional area of the wire after twisting. The limit is 0.15 to 0.3 t, and if you lower it to the currently required 0.05 to 0.15-2, the strength will still be insufficient, or even if it has strength, the conductivity will be 2.
There remained a problem that the electrical resistance would increase because the IACS was less than 0%.

In addition, the tensile strength of the conductor is 90 to 140 kgf/mw+"
.

Electric wires with a conductor breaking load of 6 kgf or more may have satisfactory static strength, but have the problem of wire breakage due to impact tension during manufacturing or impact tension during installation into an automobile.

An object of the present invention is to solve these problems and provide an electric wire conductor for automobiles that is further lightweight while ensuring reliability.

[Means to solve the problem]

The electric wire conductor for automobiles proposed by the present invention has a tensile strength of 80 to 160 kgf/ms and an elongation at break of 2% by tempering heat treatment or annealing treatment of an elementary conductor with the following structure and composition.
The conductor cross-sectional area after twisting is 0.05 to 0.31111'', the conductor breaking load T is 6 kgf or more, and the breaking elongation E is 2% or more. It is.

The conductivity of the bare conductor used is 25% IACS or higher, the surface layer is copper or copper alloy, and the excess core is 0.15 to 0°85% C.
and 0.05-0.3% Si, 0.3-1.9%
Mn, 0.5-5.0% Ni, 0.2-2.0%
Cr, 0.1~1゜0%Mo, 0.01~0
．． 2%Nb, 0.01-1.0%M, 0.001-0.
006%B, 0.1-1.0%Be, 0.02-1.
0%Aj! , one or more elements selected from 0.02 to 1.0% Ti in the above ratio, a total of 0.05% or less of P and S as unavoidable impurities, and 0.3% or less of Cu. It is a composite conductor made of steel. C in the composition of the elementary conductor is added to Si, Mn, Aj to improve hardenability and strength.
! Ni, Cr, B, Be for deoxidation and improvement of hardenability.
, Mo is Nb, ■, Mo for hardenability and prevention of temper embrittlement.
Ti is added for precipitation strengthening.

Note that the tempering heat treatment may be performed after the wire-drawn composite conductors are twisted together, or after the tempering heat treatment or annealing,
Wire drawing processing may be performed to the extent that t, T, and E can clear each specified value.

Further, the refining heat treatment mentioned here may be a continuous cooling transformation treatment such as quenching, tempering, austempering, or multi-tempering (FIG. 4).

FIG. 1 shows a cross section of the electric wire conductor of the present invention.
The illustrated electric wire conductor 1 is constructed by twisting seven elementary conductors 2 each having a diameter d. In the figure, 3 is a steel wire serving as the core of the bare conductor, and 4 is oxygen-free copper coated on the outer periphery of 3.

In order to maintain the flexibility of the electric wire conductor, it is better to have more twists in the elementary conductor 2 even if the cross-sectional area is the same.
In this case, it is necessary to prepare thin bare conductors and set a large number of bare conductors in the wire twisting machine during twisting, which is difficult, so 2 to 37 conductors, more preferably 7 to 19 is recommended.

Further, the elementary conductor used is preferably one in which the outer periphery of the metal core is coated with 20 to 80% by weight of oxygen-free copper or copper alloy.

The upper limit of the conductivity of the elementary conductor is also preferably set at 80%.

(Function) When a composite body having a copper (including alloy) coating is used as an elementary conductor, the necessary electrical conductivity (25% IACS or more) and solder adhesion can be obtained by the copper coating.

In addition, the breaking load T due to conductor tension, the holding force in the terminal housing, and the wire bending value are higher than before because steel wire containing 0.20 to 0.75% C is used as the core of the elementary conductor. Therefore, it is possible to reduce the weight by reducing the cross-sectional area of the conductor after twisting.

Here, in this invention, the tensile strength t of the elementary conductor is 80~
80 kg is limited to 160 kgf/am2
For f/mra2 or less, in the case of 7-stranded wire, the total cross-sectional area D
= 0.1mm", the conductor breaking load is less than 6kg, which may cause the wire to break or fail to provide a satisfactory terminal holding force.On the contrary, at t-160kgf/lll
A value of l112 or more is an unreasonable value because the elongation E cannot be made more than 2% simply due to wire drawing. A more desirable value of tensile strength t considering the holding force of the terminal is 90 to 140 kgf/raI
It is I2.

The reason why the elongation at break of bare conductors or stranded wires is limited to 2% or more is because if it is less than 2%, it will not be able to withstand the impact of time when manufacturing wires (terminal processing, vinyl sheathing) or assembling wires into automobiles. This is because troubles such as disconnection will increase. Preferably, E is 3% or more.

Furthermore, the reason why the conductivity of the elementary conductor is set to 25% IACS or more is based on the result of calculating the allowable current from the electrical resistance value of the conductor when the surface layer of the elementary conductor is formed of oxygen-free copper or copper alloy. If the allowable current IA is the minimum condition, the conductivity is 25% or more,
If possible, an IACS of 30 to 40% or more is optimal. Note that the upper limit of the electrical conductivity is 80% IACS when trying to maintain the necessary tensile strength using a composite, and if it exceeds this, the tensile strength will be sacrificed.

Next, the total cross-sectional area of the conductor after twisting is 0.05 to 0.30.
III112 was selected because if it is 0.30m+" or more, conventional products can obtain the required strength, but the purpose of weight reduction cannot be achieved. On the other hand, if D -0.05wm2 or less, T is 5kg or less and 710.08φ This is because the structure is prone to deformation due to tension. A more desirable value of D is 0.07 to 0.20.

Conventional annealed copper wire has a total cross-sectional area D = 0.5 m due to its mechanical properties.
Furthermore, the limit for Sn-containing copper (0.3 to 0.9Sn) is usually D=0.2mm2, but according to the present invention, D=0.1ss" ) The same strength as 0.312 products can be obtained, and the weight of the wire is reduced (for example, 0.1
2 makes it possible to achieve a reduction of 0.3■60% reduction in 2).

In addition, the reason why the carbon content of the steel wire used as the core metal of the elementary conductor is limited to 0.15 to 0.85% is because if it is less than 0.15%, the tensile strength t = 60 k
It is difficult to achieve both gf/1llt or more and elongation E=2% or more. On the other hand, the reason why the upper limit of C was set at 0.85% was that if it was higher than this, the steel wire would be extremely hard and it would not be possible to fully satisfy the tensile strength t and elongation E at the same time, and it would be extremely difficult to make the wire thinner. It depends.

The amount range of other additive elements to be included singly or in combination was regulated for the following reasons.

Si: If it is less than 0.05%, the deoxidizing effect will be weak (this will lead to an increase in oxides in the steel, worsening of wire drawing, and poor hardenability, making it impossible to obtain sufficient strength.

If it is more than 0.3%, it will become a cyst, and elongation E=2% or more is difficult.
Wire drawability also deteriorates due to embrittlement.

If Mn is less than 0.3%, deoxidizing properties and hardenability deteriorate for the same reasons as in the case of Si, and the expected secondary effect of improving corrosion resistance also decreases.

If it exceeds 1.9%, the elongation will be insufficient and the drawability will also deteriorate, as in the case of Si.

Ni: If it is less than 0.5%, no improvement in hardenability can be measured, and the expected secondary effect of improving corrosion resistance also decreases.

A content of 5% or more is not preferable because the effect of improving hardenability commensurate with the cost increase is not accompanied.

If Cr: is less than 0.2%, hardenability is not improved and strength cannot be expected to be improved, and the secondary effect of improving corrosion resistance is also reduced.

At 2.0% or more, the strength is sufficient to justify the heat treatment cost.
No improvement in elongation properties can be obtained.

B: If it is less than 0.001%, no improvement in hardenability and no improvement in strength can be expected.

If it is 0.006% or more, it will become brittle, elongation will not be obtained, and thin wire properties will deteriorate.

Be: If it is less than 0.1%, hardenability cannot be improved.

A content of 1.0% or more is not suitable because it causes embrittlement and is harmful.

Mo: If it is less than 0.1%, the effect of improving hardenability and reducing temper embrittlement is small.

If it is more than 1%, the austenitization transformation temperature (Ms humidity temperature) of the steel increases and the transformation time becomes longer, so the disadvantage of increased cost compared to the effect ratio is large (unpreferable).

Nb: If it is less than 0.01%, no effect of carbide precipitation hardening or crystal grain refinement will be produced.

If it is more than 0.2%, carbide precipitation hardening will be excessive, resulting in the same cost increase as with MO, which is inappropriate.

V: Less than 0.01%, 1.0% or more T: HaN
b (!: Same m problem comes up.

T i : If it is less than 0.02%, the addition amount will be insufficient and the effect of improving hardenability will not be achieved.

If it exceeds 1.0%, the hardenability will deteriorate or it will become difficult to shrink and draw the wire.

Af: less than 0.02% has no deoxidizing effect during dissolution.

If it is more than 1.0%, oxides such as A t2 t 03 are produced, causing troubles such as wire breakage during shrinkage drawing.

P and S: As impurities after dissolution, it is generally better to keep them at 0.05% or less.

Cu: Although the addition of a small amount has the effect of improving corrosion resistance, the addition of 0.
If it exceeds 3%, cracking during hot working, cracking during the wire drawing process after heat treatment, and wire breakage may occur, which is not suitable.

〔Example〕

As core metal materials for elementary conductors of samples P4CLl~4 shown in the table of FIG. 3, four types of 8. A steel rod of Omφ was prepared. In addition, sample N11
Oxygen-free copper (JIS3510) as coated steel pipe for l~3
A tube (hereinafter referred to as an OFC tube) was prepared.

All coated steel pipes are straight pipes with an outer diameter of 16 wφ and an inner diameter of 12 wφ.

Next, in order to obtain a composite element conductor from these materials, the surface of each of the above steel rods was dry polished (Shot Plus Ken! I).
The tube was inserted into the OFC tube with a length of L, and was squeezed with a fitting die to a diameter of about 10 m. As a result, the electrical conductivity of sample 1 is about 30%, sample 2 to 9 and 11 to 16
was about 38-40%, and sample number 10 was about 60% copper complex.

Therefore, by repeatedly drawing and softening these materials, the
■I changed it to φ. Final softening was performed by water quenching from 890°C and tempering at 200°C for samples N11l, 3-8, 13-14, and 16, and continuous cooling transformation from 890°C for sample 2. For sample 9, water quenching was performed at 890°C, tempering was performed at 400''C, and light wire drawing was performed at a rate of 15%.

Samples N11ll to 17 are comparative materials, among which sample N
ULL indicates that the degree of wire drawing is high and the elongation at break is less than 2%, and No. 12 indicates that the amount of C is outside the specified range of the present invention, and the degree of wire drawing is large and the elongation at break is less than 2%. N1113 has a C content outside the specified range of the present invention and has a tensile strength of less than 160 kgf/am+'' even after final heat treatment, and Nct14 has a C content within the specified range of the present invention. First, if the tensile strength is less than 60 kgf/an'' because the amount of other added elements is out of the range of the present invention, Inhibitor 15 is C
and Si, Mn, Cr, Nb, Ni, ■ are within the range of the present invention, but the degree of wire drawing is high and the elongation at break is less than 2%, NcL16 has a C content within the range of the present invention, Si, Mn, C
Since r, Nb, Ni, AN, and Mo were outside the scope of the present invention, oxides (inclusions) in the core material caused many wire breaks during wire drawing, and many wire breaks occurred during harness assembly. .

The tensile strength t and electrical conductivity of the elementary conductor thus obtained are as shown in the table of FIG.

After this, each elementary conductor is twisted into 7 wood wires and the total cross-sectional area D = 0.0
8 to 0.1 mm” wire conductor, Sarani, and 0
．． A 2 ml thick vinyl chloride coating was applied to the wire to make an electric wire for an automobile.

The characteristics of these electric wires are shown in the table of FIG. 3 along with the characteristics of conventional products and comparative products.

The terminal housing retention force is an important characteristic for the reliability of the connection part to the terminal in automotive electric wires, and this characteristic is determined by crimping the conductor to the terminal, then pulling the conductor in the axial direction with a tensile tester, and crimping. The load when the wire was pulled out (or broken) from the section was measured. It is desired that this holding force be 7 kg or more in most cases, preferably 10 kg or more.

Further, the tensile breaking load is desirably approximately 10 kg or more in a range where the elongation of the conductor is 3% or more, and the thicker the better.

Regarding the bending resistance of the electric wire, it is desirable that the conductor does not break when repeatedly bent, especially near the terminal portion, and this measurement is performed by placing the coated electric wire 5 in a jig 6 shown in FIG. 90° to the left and right with a load W of 500g applied to one end.
The number of times it takes to bend the tube alternately and break is shown as one round trip of 90 degrees.

Solderability was determined by immersing the specimen in white rosin flux and then immersing it in eutectic solder at 230°C for 2 seconds, then examining the ratio of the area wetted by molten solder to the total immersed surface area. A score of less than 90% was graded as poor.

As can be seen from the data in the table, when comparing the weight reduction effect of the electric wire between the inventive product and the conventional product, the total cross-sectional area D = 0.3
■The wire weight was 4.5 g/m with 2 conductors (sample Nα19), but it became 1.4 to 1.5 g/m with D-0.1 m'' (sample kl~4), about 3.0 g. /m, it was possible to reduce the weight by about 70%.The strength in this case is comparable to that of conventional products.

〔effect〕

As described above, according to the present invention, the holding force of the terminal housing, tensile breaking load, mechanical properties such as bending resistance, electrical properties, and solderability can be fully satisfied, and the large width of the wire conductor can be improved. This has the effect of contributing to suppressing increases in vehicle weight and wiring space due to an increase in the number of wiring locations, and reducing costs by reducing the amount of insulators used.

In addition, as is well known, additional elements such as Cr, Mn,
It goes without saying that the addition of Ni, Cu, etc. has the effect of improving the corrosion resistance of the core metal.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing one embodiment of the present invention, Fig. 2 is a diagram explaining the mode of the bending test, Fig. 3 (a) and (b) is a table comparing the cable characteristics, and Fig. 4 is It is a graph showing the relationship between the refining heat treatment method and Ms humidity temperature. 1...Wire conductor, 2...Elementary conductor,
3... Steel wire, 4... Oxygen-free copper, 5... Covered electric wire, 6... Jig, W... load. Figure 1 Figure 2 Figure 4 Typical cooling curves for each hardening method are shown for direct hardening multitemper and ausstepper.

Claims (3)

[Claims] (1) The tensile strength of the bare conductor before twisting is t (kgf/mm^2
), the total cross-sectional area of the conductor after stranding is D (mm^2), the conductor breaking load is T (kgf), and the elongation at break is E (%), 80<t<160, the electrical conductivity of the elementary conductor The elementary conductor satisfies the following conditions: 25% IACS or more, 0.05<D<0.30, T>6, E≧2, and the above-mentioned elementary conductor has a surface layer of copper or copper alloy and a core metal portion of carbon. 15-0.85%, other additives include 0.05-0.3% Si, 0.3-1.9% Mn, 0.
5-5.0% Ni, 0.2-2.0% Cr, 0.1-1
．． 0% Mo, 0.01-0.2% Nb, 0.01-1.
0%V, 0.001~0.006%B, 0.1~1.0
%Be, 0.02-1.0% Al, 0.02-1.0%
One or more elements selected from Ti in the above ratio, P and S as unavoidable impurities in a total of 0.05% or less, Cu
An electric wire conductor for an automobile, characterized in that it is a composite element conductor made of steel containing 0.3% or less of. (2) The electric wire conductor for an automobile according to claim 1, wherein the elementary conductor is a metal core (steel) whose outer periphery is coated with 20 to 80% by weight of oxygen-free copper or copper alloy. (3) The electric wire conductor for an automobile according to claim (1) or (2), wherein the elementary conductor has an upper limit of electrical conductivity of 80% IACS.